The role of antiarrhythmic drugs in patients with implanted cardioverter defibrillators

A significant percentage (40%-70%) of patients with implantable cardioverter-defibrillators (ICDs) receive adjunctive antiarrhythmic drug therapy, although this percentage is presently decreasing. The most common aims of drug therapy irt ICD patients are to reduce the number of ventricular arrhythmic events triggering the device, to prolong ventricular tachycardia cycle length and to increase efficacy of antitachycardia pacing, to treat combined supraventricular tachycardias and avoid inappropriate shocks, and to decrease defibrillation energy requirements. However, some antiarrhythmic agents may increase the defibrillation threshold (DFT) and/or the pacing thresholds, may slow the tachycardia below the limit for rate detection, and may cause proarrythmia. Amiodarone is particularly useful in patients with arrhythmia storm but may increase DFTs in some patients. Follow-up and appropriate device programming of patients with ICDs is particularly necessary in patients with combined antiarrhythmic drug therapy. (J Interven Cardiol 1998;11:213-216).